Understanding UMA (UMS) Ships and Their Operational Requirements

What are UMA [UMS] Ships?

The "Unattended Machinery Area" (UMA) pertains to the operation of machinery and equipment within a machinery space, where the operation occurs without the constant presence of watch-keeping personnel responsible for operational oversight during a predetermined timeframe.

The specific machinery and equipment included in this category encompass:

1. Main propulsion machinery (propulsion generating set in electric propulsion ships are excluded)
2. Controllable pitch propeller
3. Steam generating set
4. Electric generating set (propulsion generating set in electric propulsion ship are included)
5. Fuel oil systems
6. Bilge systems
7. Auxiliary machineries associated with machinery and equipment listed above

UMA ships, sometimes denoted as "UMS", must be meticulously designed and configured to ensure that the ship's safety remains at a level equivalent to that of a vessel continuously operated with watch-keeping personnel under all sailing conditions, including maneuvering. The ship's design and arrangements should be capable of facilitating the uninterrupted operation of machinery within the UMA for a minimum of 24 consecutive hours.

General Requirements of UMA(UMS) Ships

Prevention of flooding

1. High-level bilge alarm systems must be installed in bilge wells located within unattended machinery areas, and these devices should be installed in at least two different locations.
2. The controls for any valve that serves a sea inlet, a discharge point below the load water line, or a bilge suction system must be positioned in a manner that allows sufficient time for their operation in the event of water ingress into the space while the ship is fully loaded.

Fire safety measures

Fire safety measures must be implemented, with particular attention to fuel oil and lubricating oil systems. The following precautions should be observed:

1. If necessary, the fuel oil and lubricating oil piping systems should be shielded or appropriately protected to minimize the risk of oil spillage or contact with hot surfaces and air inlets.
2. Where fuel oil service tanks are filled automatically or through remote control, mechanisms must be in place to prevent overflow spillages.
3. Equipment that handles flammable liquids, such as fuel oil purifiers, should ideally be installed in dedicated spaces reserved for purifiers and their heaters, with provisions to prevent overflow spillages.
4. When heating arrangements are present in fuel oil service tanks or settling tanks, a high-temperature alarm device should be installed if there is a possibility of exceeding the fuel oil's flash point.

One of the main fire pumps should be capable of remote activation from the navigation bridge or the fire control station. Alternatively, firewater should be promptly supplied from the fire main at an appropriate pressure.

Operating requirements

Navigation bridge

The control systems on the navigation bridge and the centralized monitoring and control station should encompass the following components:

1. Bypass mechanisms, which allow temporary overriding of the program-controlled devices or other devices as deemed necessary by the Classification Society, in accordance with the requirements specified in (2). An indicator should also be included to display the activation of these bypass mechanisms.
2. The bridge control systems must incorporate program-controlled devices or alternative approved methods to ensure that the main propulsion machinery is not subjected to excessive mechanical or thermal stress. Additionally, these systems should facilitate easy adjustment of the main propulsion machinery's speed, both increasing and decreasing it, unless otherwise permitted by the Class, taking into account the type of engines and related factors. In such cases, program control devices or alternative means may be exempted as per approval by the Class.

The alarm systems located in the centralized monitoring and control station on the bridge must adhere to the following criteria. At a minimum, specific visual alarms, as mandated by the classification rules, must be installed at clearly identifiable locations within reach of the main propulsion machinery's operating controls.

1. The alarms for automatic stoppage
2. The alarms for automatic reduction of speed or load, or the alarms for demanding speed or load reduction
3. The alarms for failure of remote control systems
4. The alarms for low starting air pressure
5. The alarms for failure of remote starting
6. The alarms for prolonged running in critical speed range

The shapes, sizes, and layouts of the bridge's centralized monitoring and control station must conform to the following specifications.

1. The bridge centralized monitoring and control station is to be situated within one deck floor and not to be provided with any partition walls (steel walls, wooden walls, glass walls, etc.) inside of the station except where it is considered inevitable by the Society.
2. At the bridge centralized monitoring and control station any audible alarm and order issued from any position is to be capable of being heard clearly and directly at any other position.

Air compressor

Starting air compressors should have the ability to function automatically to sustain the pressure within the starting air reservoirs within a predefined range. Similarly, air compressors utilized for refilling the control air reservoirs should possess automatic operation capabilities to maintain the pressure within the control air reservoirs within a specified range.

Means of communication

A vocal communication system, capable of functioning even in the event of a main electrical power supply failure, should be installed to facilitate communication between the bridge's centralized monitoring and control station, the local control station for the main propulsion machinery (or a sub-control station if present), and the engineering accommodation area on ships equipped with a bridge centralized monitoring and control station. Similarly, for other ships, this communication system should link the navigating bridge, the centralized control station, the local control station for the main propulsion machinery, and the engineering accommodation.

Alarm systems

Alarm systems are to comply with the following requirements.

1. Alarm systems are to be arranged with automatic change-over to an independent standby power supply in the event of loss of the normal power supply.
2. Failure of the normal power supply and standby power supply specified in (1) is to be indicated by independent alarms.
3. Alarm devices provided on the engineers accommodation are to comply with the following requirements:
   1. Alarm devices are to be provided in engineers public rooms.
   2. Alarm devices are to be provided in the respective private rooms for engineers and to have connection to each of the engineers’ cabins through a selector switch, to ensure connection to at least a cabin of an engineer on watch.
   3. Alarm devices are to be operated with abnormal state. These alarms may be common.
4. Audible alarm devices which will provide warning of faults in machinery and equipment are to be installed in the spaces where main propulsion machinery, boilers, electric generating sets, etc. are situated.
5. Alarm devices are to be capable of activating the engineers alarm if an alarm function has not received attention at the centralized control station within a limited time.
6. For the ships provided with a bridge centralized monitoring and control station the local silencing of the audible alarms equipped in engineers’ accommodation is not to stop the audible alarm required in (5) and the audible and visual alarms equipped at the bridge centralized monitoring and control station.
7. Where unattended machinery operation is adopted, alarm systems which will provide warning of faults of Monitoring station, Control station, Main control station, Main control station on bridge, Sub-control station, Bridge control devices, Sequential control are to be such that the person on watch in the navigation bridge is made aware when:
   1. a fault has occurred,
   2. the fault is being attended to, and
   3. The fault has been rectified.

Crucial Note: The standby pumps should be automatically started following the activation of pertinent alarms, as stipulated by the Classification rules. For instance, in the event of a low-pressure alarm within the main engine lube oil system, the standby main engine lube oil pump will be automatically started.